I’m using a different browser, so YMMV.
Did you right click on the link, and then choose “Open in New Private Window” (or something roughly equivalent)?
The other thing to do is to clear WaPo cookies, but if you’re not techy that might be a stretch.
Since FF broke all my extensions I’ve switched to other browsers. Usually the steps you need to take are somewhat browser-specific. Nomenclature differs. But in general, you can poke around in your browser’s “Settings,” “Options” or “Preferences”, then find something like “Privacy” or “Security”, and look for “Cookies”. There should be tools there to let you (1) clear all cookies, or your own defined subset, usually with the aid of a search field you can type into, and (2) set “Exceptions”, which is site-specific control of how the browser interacts with that site’s cookies. For WaPo “Delete on Exit” or “Clear on Exit” as a way to handle WaPo cookies has worked for… let’s just say some people.